1. Field of the Invention
The present invention generally relates to a driveshaft supporting structure for a watercraft. More particularly, the present invention relates to a driveshaft supporting structure for supporting a driveshaft extending from an engine disposed inside the body of the watercraft to a propulsion unit disposed generally outside the body of the watercraft.
2. Description of the Related Art
Conventional jet propulsion watercraft run on water by driving a propulsion unit to aspirate water from the bottom of the body of the watercraft and emit the water rearward from the stern. In such a jet propulsion watercraft, a driveshaft extends from an engine located within an inner section of the watercraft body to the propulsion unit located within an outer section of the watercraft body to transmit the driving force of the engine to the propulsion unit. The driveshaft passes through an opening in a duct formed integrally with a hull composing the lower part of the body, and extends to the outer section of the body. The driveshaft within the inner section of the body is supported by a driveshaft supporting structure secured to the duct.
In the driveshaft supporting structure, a bearing part is provided on the outer peripheral surface of the driveshaft and a cylindrical elastic part made of rubber extends rearward from the outer peripheral surface of the bearing part. A cylindrical rubber joint, joined to the rear end of the cylindrical elastic part, is joined to the duct and surrounds the driveshaft. An annular reinforcement member is provided on the outer peripheral surface of the cylindrical elastic part, and the reinforcement member is joined via a base to a bearing part supporting section that is secured to the duct. Thus, the bearing part supporting section is secured to the duct in such a manner as to surround the cylindrical elastic part and the joint rubber.
However, in the aforementioned driveshaft supporting structure, the size of the bearing part supporting section is large owing to its construction, and thus the vacant space is small in the vicinity of the driveshaft supporting structure within the inner section of the body. This leads to a problem that the vacant space for installing other parts is small and the parts layout flexibility is restricted. Another problem is that complex work is required to secure the cylindrical elastic part to the duct via the rubber joint, and that installing the driveshaft supporting structure is bothersome because of the large number of the components. A further problem is that baking, the process generally used for securing the cylindrical elastic part and the reinforcement member, requires additional production cost.
Therefore, a need exists for a driveshaft supporting mechanism for a jet propulsion watercraft that is compact and requires less installation space, that facilitates the installation work, and that reduces the production cost of the driveshaft supporting mechanism.